TA and PH completely out of wack. Need advice.

[Crimson]

Hi all,

Visiting the in-laws with the wife. They have an above ground vinyl pool. Its about 15,000 gallons (24 ft circular by 4.5 feet deep). I brought my test kit over and here's what I got:

FC: 7
CC: 0
PH: 6.6 or less? (Its very yellow, hard to tell exactly where its at other than its really low)
TA: Test turned red immediately.. could not test as it did not turn green.. related to PH?
CH: 100 (Ok for a vinyl pool I think?)
CYA: 90 (Yes, high.. they use pucks)

Water is clear and clean. But we need to get their PH into line. According to the pool calculator I think I should be adding AT LEAST 90oz by weight of baking soda (Same as washing soda?) to try to start to get things into line and then retest. As I said I don't know what the TA is and the PH is off the charts low.. but I don't want to over-adjust.

Thoughts?

 

[257WbyMag]

I would go ahead and raise the TA with baking soda. Once you have the TA up to about 70 or 80, recheck pH.

 

[Crimson]

I would go ahead and raise the TA with baking soda. Once you have the TA up to about 70 or 80, recheck pH.

What do you think the TA is at considering it turned red immediately with the TF Testkit? Trying to get an idea of how much I should add. It never turned green like it said it would and I've never seen that before.

 

[257WbyMag]

I would go ahead and raise the TA with baking soda. Once you have the TA up to about 70 or 80, recheck pH.

What do you think the TA is at considering it turned red immediately with the TF Testkit? Trying to get an idea of how much I should add. It never turned green like it said it would and I've never seen that before.

If the TA test turns red immediately, that indicates a very low TA.

 

[257WbyMag]

I would think that the TA would have to be around 10 in order for it to turn red immediately.

 

[JasonLion]

TA has to be zero, and the PH must be extremely low, for the TA test to turn red right off.

 

[Crimson]

TA has to be zero, and the PH must be extremely low, for the TA test to turn red right off.

Threw me off as well. Never seem that with any other pool. According to the pool calculator it looks like if I am going to raise it from 0 to maybe 70 I am going to need a ton of baking soda.. 15 lbs or so? What is the best way to add it.. dissolve in a bucket of water and dump in?

 

[JasonLion]

I would start with perhaps 8 lbs of baking soda, then switch to either borax or soda ash to bring the PH up the rest of the way, and then retest the TA to see where you ended up and adjust as needed.

 

[onBalance]

Jason is right, the TA is zero.
And when the TA is zero, the pH is at 4.5. It is also possible that the pH is below 4.5 and that essentially means that the TA is a negative number.
So assume the TA is zero for now, add the bicarb, and check again to see if more is needed.

 

[257WbyMag]

Threw me off as well. Never seem that with any other pool.

We don't see it that often, but there are cases that surface occaisionally where the TA just went away. Some areas (not where I live) just don't have much TA in the fill water and that is where the problems stems usually.

 

[JamesW]

Every pound of trichlor added to a 15,000 gallon pool will lower the TA by about 5.2 ppm. 20 pounds of trichlor would add 90 ppm of cyanuric acid and lower the TA by 104 ppm.

Once you add the bicarb, you should aerate the water as much as possible to offgass the carbon dioxide that will be created from adding the bicarb.

People should not get in the water until the pH is between 7.2 to 7.8.

If there are metals in the water, then they might drop out as the pH rises. Copper would be the most problematic. If they have, or had, a heater or an ionizer, or ever used copper algaecide, then they might get copper stains. The stains might be turquoise, black, grey or even amethyst (purple/violet).

 

[Crimson]

Added 8 lbs of baking soda, TA is now ~30 PH is still below 6.8.

 

[Butterfly]

Added 8 lbs of baking soda, TA is now ~30 PH is still below 6.8.

Time to use borax or soda ash to get the ph up in the low 7's. Then test and adjust TA.

 

[Crimson]

So don't keep adding the baking soda even though the TA is so low yet?

 

[Crimson]

Oops sorry I actually added 12 lbs of baking soda. TA 30 PH still too low to measure on the color chart.

 

[Butterfly]

So don't keep adding the baking soda even though the TA is so low yet?

Yes, start working on the pH and get it to the low 7's. Borax and soda ash will raise the pH and also raise the TA a little with it.

Once you get the pH in the low 7's, retest the TA and adjust.